Answer:
1. Density can be used to identify a substance
2. Density can be used to ascertain whether a substance will float in water.
Explanation:
The calculation of the density of a substance can be used to identify the substance. If the density of a substance is calculated accurately, and compared with a table of standard densities, then we can identify that substance.
Also, density determines whether an object will float or sink in water. If an object is less dense than water then it will float in water. If it is denser than water, then it will sink in water.
Answer: Option (D) is the correct answer.
Explanation:
The chemical reaction equation will be as follows.

This means a new substance has been formed and a chemical change has taken place.
A chemical reaction in which heat energy is absorbed by the reactant molecules is known as an endothermic reaction.
For example,
On the other hand, a chemical reaction in which heat energy is released by the reactant molecules is known as an exothermic reaction.
For example,
is an exothermic reaction.
Thus, we can conclude that in the given situation the beaker most likely felt warm because a chemical reaction was producing a new substance.
Answer:
6.grass
7.xylem
8.oval
9. poor growth of bones and teetn
Answer:
Rb
Alkali Metals are Group 1 so
Rb it isnt Hydrogen because it is a gas
Explanation: